Referring to FIG. 1, a conventional front-mounted roller type elliptical exercise machine 1 includes a base 11, a resisting flywheel unit 12 disposed at a front of the base 11, a console 13 disposed above the resisting flywheel unit 12, a track seat 14 disposed rearwardly of the base 11, two transmitting rods 15 each having an end pivotably connected to the resisting flywheel unit 12 and an opposite end having a roller 18 that is slidable along the track seat 14, two pedal rods 16 pivotably connected to the transmitting rods 15, respectively, and two foot pedals 17 respectively affixed on rear ends of the pedal rods 16. When a user treads on the foot pedals 17, the rollers 18 roll along the track seat 14, which results in a reciprocating movement along an elliptical route of the pedal rods 16. However, the track seat 14 needs to be maintained by using lubricant to reduce friction and noise generated during rolling of the rollers 18. Furthermore, dirt and grime accumulation on the track seat 14 may adversely affect smoothness in operation and may shorten the service life of the machine 1.
Referring to FIG. 2, a conventional rear-mounted suspension type elliptical exercise machine 2 includes a base 21, a console 22 disposed at a front of the base 21, a resisting flywheel unit 23 disposed at a rear of the base 21, two pedal rods 24 pivotably connected to the resisting flywheel unit 23, and two foot pedals 25 respectively affixed on rear ends of the pedal rods 24. Due to the positions and orientations of the resisting flywheel unit 23 and the console 22, the elliptical exercise machine 2 is relative large and bulky. Moreover, the user can step on the foot pedals 25 only from two lateral sides of the base 21, which results in inconvenient usage.